Field of the Invention
The present invention is directed to a micropump adapted for the continuous delivery of a liquid medication by infusion such as may be used in the delivery of insulin for the treatment of diabetes.
Description of the Related Art
Micropumps for subcutaneous delivery of drugs are known, for example, from U.S. Pat. Nos. 7,726,955 and 8,282,366. This prior art describes, in various embodiments, a pump having a rotor mounted in a stator, or housing. Sealing rings situated at an angle on axial extensions on the rotor cooperate with channels formed between the rotor and the stator to move liquid in precise amounts through a rotor housing. However, these embodiments are relatively complex and not cost effective. The user keeps the pump when the infusion patch is changed for several weeks. As the art continues to evolve toward fully disposable pumps, the need for compact and economical micropump designs remains acute.
Another infusion pump known in the prior art comprises a rigid reservoir with a lead screw engaged in the reservoir to dispense medication through a cannula as the lead screw advances. In this arrangement, the actuator for delivery of the medication is directly connected to the lead screw and dosing precision depends on variables that are difficult to control, such as the precision of the motor. Moreover, the device requires the rigid reservoir to provide calibrated dosages. Thus, it is impossible to use a flexible reservoir and the number of possible layouts for the pump is consequently limited.